Hives are a red, raised itchy rash which develops on the skin as a result of an allergic reaction. They appear when histamine is released within the skin as a response to an irritant, allergen, infection or certain medications.
Another name for hives is urticaria.
There are two types of hives:
- Acute hives
- Chronic hives
Acute hives lasts for less then 6 weeks whereas chronic hives persists for longer. There are different causes of both these types of hives.
The acute version is more common and affects 1 in 5 people, mainly children. Chronic hives accounts for only 1 in 1,000 cases.
Causes of hives
Hives are caused by the release of histamine but this differs between the acute and chronic versions.
These are triggered by the following:
- Allergen (substances which causes an allergic reaction): these include nuts, shellfish or eggs.
- Irritant: these include chemicals, solvents or detergents. Substances which irritate the skin.
- Environmental factors: examples of these include direct sunlight and water.
- Infection: cold or flu
- Medication: certain forms of medication such as non-steroidal anti-inflammatory drugs (NSAID’s) are another cause of hives.
These occur for entirely different reasons. They often develop as an autoimmune reaction caused by the body’s immune system turning upon itself, releasing antibodies which attack cells containing histamine. And histamine is a known trigger for hives.
Experts are unsure as to the exact cause of autoimmune chronic hives.
There are a few rare cases where chronic hives develop as a reaction to another medical condition, for example viral hepatitis. But thankfully, this is rare.
Chronic hives tends to come and go so if you develop this version then expect flare ups and periods of remission. Stress, caffeine, alcohol, warm environments and tight clothing will cause a flare up so limit your consumption/exposure to these triggers.
Symptoms of hives
The main feature of hives is a raised, pink or red skin rash which is itchy and varies in size. The spots or lesions range in size from a few centimetres to large unsightly patches.
They develop after a few hours and cover across a single area of the body or several areas at once. This rash subsides within 24 hours and the skin returns to its normal state.
A less well known version called urticaria vasculitis often results in bruising although this is very rare. If you develop a rash which lasts for longer than 24 hours, is painful and leaves a bruise then see your GP. He or she will refer you immediately to a dermatologist.
See your GP irrespective of which type of hives you develop. Your GP will ask you about your rash and medical history before examining the infected areas. He/she will determine whether you have acute or chronic hives.
If your GP suspects you have acute hives then he/she will ask you about foods you have eaten or substances you have touched or handled which may have triggered this outbreak. You will also be asked if there is a history of hives within your family.
If your hives has occurred as an allergic reaction then you will be referred to a clinic for allergy testing. Allergy testing takes the form of a patch test in which certain substances are applied to your skin to see if there is a reaction. A blood test may also be performed.
However, if your GP thinks you may have chronic hives then allergy testing will not be performed as the chronic type is not usually caused by an allergy.
But your GP will refer you for tests to determine the underlying cause. He or she will also ask you about your lifestyle which includes how much alcohol you consume (if you drink), your stress levels, caffeine intake and if you are taking any medication.
The tests will include a blood test, thyroid and liver function tests and an erythrocyte sedimentation rate (ESR) test which checks the condition of your immune system.
Treatment for hives
This depends upon the type of hives you are diagnosed with.
If you have acute hives then you may not require treatment as this usually clears up by itself. But more serious cases of acute hives can be treated with antihistamines or corticosteroids. These are prescribed by your GP.
The aim is to suppress the release of histamine which will reduce the risk of any itchy rash.
But if you have chronic hives then you will be referred to a dermatologist. He or she will look at ways in which you can manage the symptoms and avoiding substances that trigger an outbreak, for example, reducing your caffeine intake.
Treatment will involve:
- Menthol creams
This also includes making changes to your diet. Avoid foods which cause histamine to be released such as shellfish, strawberries, chocolate and pineapple.
Minimise your intake of foods which contain salicylates (aspirin like compounds) that also trigger an outbreak. These include tomatoes, tea, orange juice and spices.
This is a complication of acute hives. It takes the form of swellings in the deeper layers of the skin, e.g. mouth, which causes a burning but not itchy feeling. It eases after a few days.
But obtain urgent medical attention if you have problems with breathing or develop symptoms of anaphylactic shock. These include breathing difficulties, swelling of the throat, nausea and a rapid heartbeat. Call 999 if this occurs.